1 // SPDX-License-Identifier: GPL-2.0-only
2 /*
3 * Copyright (C) 2012,2013 - ARM Ltd
4 * Author: Marc Zyngier <marc.zyngier@arm.com>
5 *
6 * Derived from arch/arm/kvm/handle_exit.c:
7 * Copyright (C) 2012 - Virtual Open Systems and Columbia University
8 * Author: Christoffer Dall <c.dall@virtualopensystems.com>
9 */
10
11 #include <linux/kvm.h>
12 #include <linux/kvm_host.h>
13
14 #include <asm/esr.h>
15 #include <asm/exception.h>
16 #include <asm/kvm_asm.h>
17 #include <asm/kvm_emulate.h>
18 #include <asm/kvm_mmu.h>
19 #include <asm/debug-monitors.h>
20 #include <asm/traps.h>
21
22 #include <kvm/arm_hypercalls.h>
23
24 #define CREATE_TRACE_POINTS
25 #include "trace_handle_exit.h"
26
27 typedef int (*exit_handle_fn)(struct kvm_vcpu *);
28
kvm_handle_guest_serror(struct kvm_vcpu * vcpu,u32 esr)29 static void kvm_handle_guest_serror(struct kvm_vcpu *vcpu, u32 esr)
30 {
31 if (!arm64_is_ras_serror(esr) || arm64_is_fatal_ras_serror(NULL, esr))
32 kvm_inject_vabt(vcpu);
33 }
34
handle_hvc(struct kvm_vcpu * vcpu)35 static int handle_hvc(struct kvm_vcpu *vcpu)
36 {
37 int ret;
38
39 trace_kvm_hvc_arm64(*vcpu_pc(vcpu), vcpu_get_reg(vcpu, 0),
40 kvm_vcpu_hvc_get_imm(vcpu));
41 vcpu->stat.hvc_exit_stat++;
42
43 ret = kvm_hvc_call_handler(vcpu);
44 if (ret < 0) {
45 vcpu_set_reg(vcpu, 0, ~0UL);
46 return 1;
47 }
48
49 return ret;
50 }
51
handle_smc(struct kvm_vcpu * vcpu)52 static int handle_smc(struct kvm_vcpu *vcpu)
53 {
54 /*
55 * "If an SMC instruction executed at Non-secure EL1 is
56 * trapped to EL2 because HCR_EL2.TSC is 1, the exception is a
57 * Trap exception, not a Secure Monitor Call exception [...]"
58 *
59 * We need to advance the PC after the trap, as it would
60 * otherwise return to the same address...
61 */
62 vcpu_set_reg(vcpu, 0, ~0UL);
63 kvm_incr_pc(vcpu);
64 return 1;
65 }
66
67 /*
68 * Guest access to FP/ASIMD registers are routed to this handler only
69 * when the system doesn't support FP/ASIMD.
70 */
handle_no_fpsimd(struct kvm_vcpu * vcpu)71 static int handle_no_fpsimd(struct kvm_vcpu *vcpu)
72 {
73 kvm_inject_undefined(vcpu);
74 return 1;
75 }
76
77 /**
78 * kvm_handle_wfx - handle a wait-for-interrupts or wait-for-event
79 * instruction executed by a guest
80 *
81 * @vcpu: the vcpu pointer
82 *
83 * WFE: Yield the CPU and come back to this vcpu when the scheduler
84 * decides to.
85 * WFI: Simply call kvm_vcpu_block(), which will halt execution of
86 * world-switches and schedule other host processes until there is an
87 * incoming IRQ or FIQ to the VM.
88 */
kvm_handle_wfx(struct kvm_vcpu * vcpu)89 static int kvm_handle_wfx(struct kvm_vcpu *vcpu)
90 {
91 if (kvm_vcpu_get_esr(vcpu) & ESR_ELx_WFx_ISS_WFE) {
92 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), true);
93 vcpu->stat.wfe_exit_stat++;
94 kvm_vcpu_on_spin(vcpu, vcpu_mode_priv(vcpu));
95 } else {
96 trace_kvm_wfx_arm64(*vcpu_pc(vcpu), false);
97 vcpu->stat.wfi_exit_stat++;
98 kvm_vcpu_block(vcpu);
99 kvm_clear_request(KVM_REQ_UNHALT, vcpu);
100 }
101
102 kvm_incr_pc(vcpu);
103
104 return 1;
105 }
106
107 /**
108 * kvm_handle_guest_debug - handle a debug exception instruction
109 *
110 * @vcpu: the vcpu pointer
111 *
112 * We route all debug exceptions through the same handler. If both the
113 * guest and host are using the same debug facilities it will be up to
114 * userspace to re-inject the correct exception for guest delivery.
115 *
116 * @return: 0 (while setting vcpu->run->exit_reason)
117 */
kvm_handle_guest_debug(struct kvm_vcpu * vcpu)118 static int kvm_handle_guest_debug(struct kvm_vcpu *vcpu)
119 {
120 struct kvm_run *run = vcpu->run;
121 u32 esr = kvm_vcpu_get_esr(vcpu);
122
123 run->exit_reason = KVM_EXIT_DEBUG;
124 run->debug.arch.hsr = esr;
125
126 if (ESR_ELx_EC(esr) == ESR_ELx_EC_WATCHPT_LOW)
127 run->debug.arch.far = vcpu->arch.fault.far_el2;
128
129 return 0;
130 }
131
kvm_handle_unknown_ec(struct kvm_vcpu * vcpu)132 static int kvm_handle_unknown_ec(struct kvm_vcpu *vcpu)
133 {
134 u32 esr = kvm_vcpu_get_esr(vcpu);
135
136 kvm_pr_unimpl("Unknown exception class: esr: %#08x -- %s\n",
137 esr, esr_get_class_string(esr));
138
139 kvm_inject_undefined(vcpu);
140 return 1;
141 }
142
handle_sve(struct kvm_vcpu * vcpu)143 static int handle_sve(struct kvm_vcpu *vcpu)
144 {
145 /* Until SVE is supported for guests: */
146 kvm_inject_undefined(vcpu);
147 return 1;
148 }
149
150 /*
151 * Guest usage of a ptrauth instruction (which the guest EL1 did not turn into
152 * a NOP). If we get here, it is that we didn't fixup ptrauth on exit, and all
153 * that we can do is give the guest an UNDEF.
154 */
kvm_handle_ptrauth(struct kvm_vcpu * vcpu)155 static int kvm_handle_ptrauth(struct kvm_vcpu *vcpu)
156 {
157 kvm_inject_undefined(vcpu);
158 return 1;
159 }
160
161 static exit_handle_fn arm_exit_handlers[] = {
162 [0 ... ESR_ELx_EC_MAX] = kvm_handle_unknown_ec,
163 [ESR_ELx_EC_WFx] = kvm_handle_wfx,
164 [ESR_ELx_EC_CP15_32] = kvm_handle_cp15_32,
165 [ESR_ELx_EC_CP15_64] = kvm_handle_cp15_64,
166 [ESR_ELx_EC_CP14_MR] = kvm_handle_cp14_32,
167 [ESR_ELx_EC_CP14_LS] = kvm_handle_cp14_load_store,
168 [ESR_ELx_EC_CP14_64] = kvm_handle_cp14_64,
169 [ESR_ELx_EC_HVC32] = handle_hvc,
170 [ESR_ELx_EC_SMC32] = handle_smc,
171 [ESR_ELx_EC_HVC64] = handle_hvc,
172 [ESR_ELx_EC_SMC64] = handle_smc,
173 [ESR_ELx_EC_SYS64] = kvm_handle_sys_reg,
174 [ESR_ELx_EC_SVE] = handle_sve,
175 [ESR_ELx_EC_IABT_LOW] = kvm_handle_guest_abort,
176 [ESR_ELx_EC_DABT_LOW] = kvm_handle_guest_abort,
177 [ESR_ELx_EC_SOFTSTP_LOW]= kvm_handle_guest_debug,
178 [ESR_ELx_EC_WATCHPT_LOW]= kvm_handle_guest_debug,
179 [ESR_ELx_EC_BREAKPT_LOW]= kvm_handle_guest_debug,
180 [ESR_ELx_EC_BKPT32] = kvm_handle_guest_debug,
181 [ESR_ELx_EC_BRK64] = kvm_handle_guest_debug,
182 [ESR_ELx_EC_FP_ASIMD] = handle_no_fpsimd,
183 [ESR_ELx_EC_PAC] = kvm_handle_ptrauth,
184 };
185
kvm_get_exit_handler(struct kvm_vcpu * vcpu)186 static exit_handle_fn kvm_get_exit_handler(struct kvm_vcpu *vcpu)
187 {
188 u32 esr = kvm_vcpu_get_esr(vcpu);
189 u8 esr_ec = ESR_ELx_EC(esr);
190
191 return arm_exit_handlers[esr_ec];
192 }
193
194 /*
195 * We may be single-stepping an emulated instruction. If the emulation
196 * has been completed in the kernel, we can return to userspace with a
197 * KVM_EXIT_DEBUG, otherwise userspace needs to complete its
198 * emulation first.
199 */
handle_trap_exceptions(struct kvm_vcpu * vcpu)200 static int handle_trap_exceptions(struct kvm_vcpu *vcpu)
201 {
202 int handled;
203
204 /*
205 * See ARM ARM B1.14.1: "Hyp traps on instructions
206 * that fail their condition code check"
207 */
208 if (!kvm_condition_valid(vcpu)) {
209 kvm_incr_pc(vcpu);
210 handled = 1;
211 } else {
212 exit_handle_fn exit_handler;
213
214 exit_handler = kvm_get_exit_handler(vcpu);
215 handled = exit_handler(vcpu);
216 }
217
218 return handled;
219 }
220
221 /*
222 * Return > 0 to return to guest, < 0 on error, 0 (and set exit_reason) on
223 * proper exit to userspace.
224 */
handle_exit(struct kvm_vcpu * vcpu,int exception_index)225 int handle_exit(struct kvm_vcpu *vcpu, int exception_index)
226 {
227 struct kvm_run *run = vcpu->run;
228
229 exception_index = ARM_EXCEPTION_CODE(exception_index);
230
231 switch (exception_index) {
232 case ARM_EXCEPTION_IRQ:
233 return 1;
234 case ARM_EXCEPTION_EL1_SERROR:
235 return 1;
236 case ARM_EXCEPTION_TRAP:
237 return handle_trap_exceptions(vcpu);
238 case ARM_EXCEPTION_HYP_GONE:
239 /*
240 * EL2 has been reset to the hyp-stub. This happens when a guest
241 * is pre-empted by kvm_reboot()'s shutdown call.
242 */
243 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
244 return 0;
245 case ARM_EXCEPTION_IL:
246 /*
247 * We attempted an illegal exception return. Guest state must
248 * have been corrupted somehow. Give up.
249 */
250 run->exit_reason = KVM_EXIT_FAIL_ENTRY;
251 return -EINVAL;
252 default:
253 kvm_pr_unimpl("Unsupported exception type: %d",
254 exception_index);
255 run->exit_reason = KVM_EXIT_INTERNAL_ERROR;
256 return 0;
257 }
258 }
259
260 /* For exit types that need handling before we can be preempted */
handle_exit_early(struct kvm_vcpu * vcpu,int exception_index)261 void handle_exit_early(struct kvm_vcpu *vcpu, int exception_index)
262 {
263 if (ARM_SERROR_PENDING(exception_index)) {
264 if (this_cpu_has_cap(ARM64_HAS_RAS_EXTN)) {
265 u64 disr = kvm_vcpu_get_disr(vcpu);
266
267 kvm_handle_guest_serror(vcpu, disr_to_esr(disr));
268 } else {
269 kvm_inject_vabt(vcpu);
270 }
271
272 return;
273 }
274
275 exception_index = ARM_EXCEPTION_CODE(exception_index);
276
277 if (exception_index == ARM_EXCEPTION_EL1_SERROR)
278 kvm_handle_guest_serror(vcpu, kvm_vcpu_get_esr(vcpu));
279 }
280
nvhe_hyp_panic_handler(u64 esr,u64 spsr,u64 elr_virt,u64 elr_phys,u64 par,uintptr_t vcpu,u64 far,u64 hpfar)281 void __noreturn __cold nvhe_hyp_panic_handler(u64 esr, u64 spsr,
282 u64 elr_virt, u64 elr_phys,
283 u64 par, uintptr_t vcpu,
284 u64 far, u64 hpfar) {
285 u64 elr_in_kimg = __phys_to_kimg(elr_phys);
286 u64 hyp_offset = elr_in_kimg - kaslr_offset() - elr_virt;
287 u64 mode = spsr & PSR_MODE_MASK;
288
289 /*
290 * The nVHE hyp symbols are not included by kallsyms to avoid issues
291 * with aliasing. That means that the symbols cannot be printed with the
292 * "%pS" format specifier, so fall back to the vmlinux address if
293 * there's no better option.
294 */
295 if (mode != PSR_MODE_EL2t && mode != PSR_MODE_EL2h) {
296 kvm_err("Invalid host exception to nVHE hyp!\n");
297 } else if (ESR_ELx_EC(esr) == ESR_ELx_EC_BRK64 &&
298 (esr & ESR_ELx_BRK64_ISS_COMMENT_MASK) == BUG_BRK_IMM) {
299 const char *file = NULL;
300 unsigned int line = 0;
301
302 /* All hyp bugs, including warnings, are treated as fatal. */
303 if (!is_protected_kvm_enabled() ||
304 IS_ENABLED(CONFIG_NVHE_EL2_DEBUG)) {
305 struct bug_entry *bug = find_bug(elr_in_kimg);
306
307 if (bug)
308 bug_get_file_line(bug, &file, &line);
309 }
310
311 if (file)
312 kvm_err("nVHE hyp BUG at: %s:%u!\n", file, line);
313 else
314 kvm_err("nVHE hyp BUG at: %016llx!\n", elr_virt + hyp_offset);
315 } else {
316 kvm_err("nVHE hyp panic at: %016llx!\n", elr_virt + hyp_offset);
317 }
318
319 /*
320 * Hyp has panicked and we're going to handle that by panicking the
321 * kernel. The kernel offset will be revealed in the panic so we're
322 * also safe to reveal the hyp offset as a debugging aid for translating
323 * hyp VAs to vmlinux addresses.
324 */
325 kvm_err("Hyp Offset: 0x%llx\n", hyp_offset);
326
327 panic("HYP panic:\nPS:%08llx PC:%016llx ESR:%08llx\nFAR:%016llx HPFAR:%016llx PAR:%016llx\nVCPU:%016lx\n",
328 spsr, elr_virt, esr, far, hpfar, par, vcpu);
329 }
330